1. Technical Field
Devices and systems for disinfecting contaminated articles are described herein. Methods for determining operating conditions for the devices and systems described herein, as well as methods for disinfecting contaminated articles, are also provided.
2. Description of the Related Art
Proper disinfection or sterilization of reusable medical instruments is important in preventing the person-to-person transmission of pathogenic microbes. The level of sterilization and disinfection applied to medical instruments depends on how the device is classified. The Centers for Disease Control (CDC) classifies a medical instrument as a critical item, semi critical item, or noncritical item, depending on the intended use of the device (CDC Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008). In the CDC Guideline, it is stated that critical items confer a high risk for infection if they are contaminated with any microorganism.
Examples of critical items are devices that contact sterile tissue and include surgical instruments, implants, and ultrasound probes used in sterile body cavities. These devices must be sterilized prior to use.
Semi critical items typically contact mucous membranes or non-intact skin. Exemplary semi critical items include such devices as probes used in vaginal, rectal, and urological exams, equipment for respiratory therapy and anesthesia, and certain endoscopes. These medical devices should be free from all microorganisms; however, some small numbers of bacterial spores are considered permissible. Semi critical items require at least high level disinfection (HLD).
Noncritical items are those that come in contact with non-mucous membranes of intact skin (e.g., blood pressure cuffs and stethoscopes). In contrast to critical and some semi critical items, which are often disinfected with large, fixed, disinfection systems, most noncritical reusable items may be decontaminated where they are used to achieve intermediate or low levels of disinfection, and these items typically do not need to be transported to a central processing area for service.
Because critical items confer a high risk for infection when they are contaminated with any microorganism, they are typically subjected to sterilization processes that kill and remove all microorganisms. Similarly, semi-critical items require high-level disinfection (HLD) where population levels of pathogens are reduced to very low levels prior to or between uses. The most common methods for achieving sterilization or high-level disinfection include treatments using high temperature steam and/or chemical disinfectants. Chemical treatments are often used where the article to be treated is heat sensitive, and chemical disinfectants suitable for use in sterilizing or disinfecting medical devices include, for example, glutaraldehyde, hydrogen peroxide, ortho-phthalaldehyde, and peracetic acid with hydrogen peroxide. Currently, the most common methods for achieving high level disinfection of semi-critical medical devices include soaking the devices in a chemical bath. The chemical bath method for semi-critical items may include achieving HLD by soaking for shorter periods of time than would be required to assure complete sterilization.
Although effective, there are disadvantages to sterilization and disinfection processes that utilize steam or chemical treatments. For example, the high temperature associated with steam sterilization can damage the instrument being sterilized. Additionally, the chemicals used for chemical sterilization or disinfection are often costly to store and dispose of properly, and their toxicity can present risks to personnel handling them. Another disadvantage of chemical sterilization is that in many cases, only a portion of an instrument is immersed or otherwise exposed to the chemical solution. Immersing a portion of a medical device in a disinfectant bath commonly treats only that portion of the device, leaving other parts potentially contaminated. Furthermore, chemical methods and high heat (i.e., severe heating to high temperatures in steam) systems can cause degradation of the materials used to make the medical device being treated. Steam- or chemical-based processes can also be time consuming with some procedures taking between 15-40 minutes to complete, and these procedures typically require the instrument or device to be removed to a central location for treatment and then returned to the clinical setting. Such prolonged process times remove medical devices from service, which may be a serious problem if the device is used in an Emergency Department setting. Another problem with removing a medical device from service is related to the installation of the device in the medical setting. Often, medical devices are coupled to central power, communications, or other control equipment. Frequent disconnection and reconnection of medical devices that are tethered to a control unit causes wear and tear and often induces failure at the connector. The cost of implementing containment and safety systems required, in particular those for chemical disinfecting systems (such as fume hoods, dedicated service rooms, and chemical waste systems), makes it difficult in practice for many clinics and small medical groups to employ them. Factors such as these can lead to non-compliance with the sterilization or disinfection procedures for reusable medical devices recommended by the Food and Drug Administration.